•Continuous-time approach for scheduling of multi-source pipeline systems.•Parallel batch injections and simultaneous product deliveries to multiple terminals.•The problem goal is to minimize flow ...restart and pump switching costs.•Detailed scheduling of pumping and batch-cut operations is provided.•Specific flow-rate ranges for each pipeline segment are easily managed.
Pipeline networks are the shippers’ first choice for carrying large volumes of refined petroleum products from oil refineries to distant distribution terminals. Optimization approaches for solving the pipeline scheduling problem proceed in two hierarchical stages: the aggregate and the detailed planning steps. The aggregate plan determines the batch sizes, the sequence of batch injections, and the allocation of batches to customers. The subsequent stage refines the aggregate plan to find the detailed schedule of batch input and output operations. This paper presents a mixed-integer linear programming (MILP) formulation for the detailed scheduling of multi-source pipelines that accounts for parallel batch injections and simultaneous product deliveries to multiple terminals. It overcomes a critical drawback of previous models that assume single source configurations. Modeling multi-source pipeline networks is a great challenge, requiring a completely revised approach. The new model finds cost-effective solutions with remarkable efficiency.
The predictive capacity of models is becoming increasingly relevant due to the increase in the development and deployment of digital twins in several areas of manufacturing. Therefore, it is ...important to keep the models up to date so that they represent the process reliably. One way to keep these models calibrated is via parameter estimation. However, parameter estimation problems in nonlinearly parametrized systems result in local optima or suffer from high computational costs. In view of the aforementioned limitations, multiple shooting parameter estimation arises as viable method, since it provides a setting to deal with the ill-defined regions of the search space. In this paper, we propose an improvement to the multiple shooting parameter estimation integrating sensitivity analysis. The approach divides the measured operating trajectory into different segments and performs a sensitivity analysis to find the most contributing parameters in each of these segments. In this way, the proposed technique benefits from the selection of a subset of the most sensitive parameters per segment and the computational advantages of the multiple shooting method. The performance of the multiple shooting parameter estimation integrated with sensitivity analysis is tested on a case study, a batch reactive distillation column which is a multistage process.
•An unsupervised sentence representation (embedding) method is proposed.•Our method uses word embeddings and Information Theoretic principles behind TF–IDF.•Word embeddings of a sentence contribute ...with their associated word information.•The proposed method is modular and identifiable at sentence level.•Results on well-known sentence similarity benchmarks are highly competitive.
Sentence representation at the semantic level is a challenging task for natural language processing and Artificial Intelligence. Despite the advances in word embeddings (i.e. word vector representations), capturing sentence meaning is an open question due to complexities of semantic interactions among words. In this paper, we present an embedding method, which is aimed at learning unsupervised sentence representations from unlabeled text. We propose an unsupervised method that models a sentence as a weighted series of word embeddings. The weights of the series are fitted by using Shannon’s Mutual Information (MI) among words, sentences and the corpus. In fact, the Term Frequency–Inverse Document Frequency transform (TF–IDF) is a reliable estimate of such MI. Our method offers advantages over existing ones: identifiable modules, short-term training, online inference of (unseen) sentence representations, as well as independence from domain, external knowledge and linguistic annotation resources. Results showed that our model, despite its concreteness and low computational cost, was competitive with the state of the art in well-known Semantic Textual Similarity (STS) tasks.
Fiber-reinforced biological soft tissues are often modeled as anisotropic hyperelastic materials. Four strain invariants can be used to define a strain energy function for soft tissues reinforced ...with a single fiber family: two isotropic invariants I1,I2 and two anisotropic invariants I4,I5. Invariant I5 is often omitted in the strain energy functions to simplify the problem mathematically. In this study, the implications of using only I4 or the use of both anisotropic invariants I4,I5 in the numerical modeling of soft tissues were analyzed. A simple modification to the Holzapfel–Gasser–Ogden (HGO) model is proposed by adding a term that contains invariant I5. Material parameters were calculated by fitting the models with experimental data of uniaxial traction in the tibialis anterior tendon tissue of rats. General analytical solutions for the simple load scenarios were obtained. Such solutions are taken as a reference point to measure the precision of the numerical results obtained in the finite element simulations. The main differences between the models were observed in the shear behavior. The proposed model predicts three different shear responses (two responses with fiber reinforcement and one isotropic response), while the HGO model predicts two equal isotropic responses and only one with fiber reinforcement. Two sets of simple shear experimental data on a fiber-reinforced elastomer material were used to verify the shear stress prediction of the models. The experimental data show that the three shear behaviors are different; thus, the HGO model offers a limited description of the shear behavior. Furthermore, analytical solutions and experimental data suggest that invariant I5 is related to the elastic energy of the fibers when the material is subjected to shear in a direction parallel to the fibers. The models for non-homogeneous deformations were also compared. For this comparison, an irregular geometry was implemented in ABAQUS, and the traction and shear conditions were simulated by changing the fiber inclination. The most critical difference was found when the shear was parallel to the direction of the fiber and the minor difference when the fiber was at 45° to the load force.
•A numerical comparison on the use of one or both anisotropic invariants is presented.•In order to show the role of anisotropic invariants, a modification to HGO model is proposed.•Numerical predictions of the models in finite element simulations are investigated.•We show that the I5 can represent the elastic energy of the fiber when the tissue is under shear in the fiber direction.
This article offers a theoretical reflection about how the power relations within the international political system configure national recognition in the context of sport. Theoretical developments ...of soft power are complemented with a neoclassical realist approach, due to the fact that countries shape their sports policies and estimate their potential scope and impact according to their relative capacities in the international scenario.
The starting point is that states and sub-state governments pursue the same political goals in international sport: influencing international arena through diplomatic strategies, increasing patriotism and the nation´s international prestige through the organisation of sports mega-events, legitimising their - regional or national - governments through medals and victories, etc. However, only the states are initially legitimised to achieve such goals due to the sports statehood, meaning in this context that International Sports Federations and International Olympic Committee define the term country as an independent state recognised by the international community.
Analysing the cases of China-Taiwan and Serbia-Kosovo, the conclusion is that without a consensus between the disputing parties, national recognition in international sport will not depend so much on the development of a soft power strategy, but on the relative capacities of countries to impose their political criterion in the United Nations, the International Olympic Committee and the International Sports Federations.
This paper studies Latin American sport from an International Relations perspective. Considering that systemic imperatives are overlooked in most sports studies and that power is not conceived as a ...comprehensive element that drives state action, the focus here is to study the relationship between the international power structure and sports performance, analysing the correlation between the World Power Index (WPI) and the medal table of the Pan-American Games from the edition of Mexico City 1975 to Lima 2019. The results show that there is a positive and strong correlation in the different periods of time evaluated, but even with that, we do not defend that there is an automatic conversion of national power into the medal tables at the Pan-American Games. In conclusion, this article argues that from International Relations, the International Structure configures the medal plans of countries, namely, where they want to be positioned in the final rankings, which in the end, shapes the medal table of sports competitions.
Lichen planus pigmentosus (LPP) is considered a rare variant of lichen planus (LP). It is characterized by acquired dark brown to gray macular pigmentation located on sun‐exposed areas of the face, ...neck, and flexures, commonly found in dark‐skinned patients. In patients with LPP, an inflammatory lichenoid response results in marked pigmentary incontinence. It has been associated with hepatitis C virus, sun exposure, and contactants such as mustard oil and nickel. LPP‐inversus affects fair and dark skin, predominantly involving flexural and intertriginous areas, while sun‐exposed areas are spared; friction is an associated trigger. LPP along Blaschko's lines has been associated with susceptibility to genetic mosaicisms. LPP can present concomitantly with other variants of LP such as frontal fibrosing alopecia, as well as endocrinopathies, and autoimmune diseases. Treatment is difficult and consists of avoidance of triggers and topical and systemic medications in order to stop the inflammatory reaction and reduce pigmentation, improving aesthetic appearance and quality of life.
To assess whether the psychological variables perceived stress, neuroticism and coping strategies, are associated with Premenstrual Syndrome (PMS) and Premenstrual Dysphoric Syndrome (PMDD).
...Case-control study with incident cases using the Spanish public healthcare system.
3 major public hospitals and one family counseling and planning center.
Women consulting for troubles related to menstruation and for other motives such as screening for uterine cancer, contraception counselling or desire for pregnancy.
Logistic regression.
Odds of PMS and PMDD.
285 PMS and 285 age-matched controls, as well as 88 PMDD cases and 176 controls participated in the study. Medium and high levels of perceived stress were associated with an increase in the odds of PMS (Odds Ratio (OR) = 2.49; 95%CI: 1.41-4.39 and OR = 4.90; 95%CI: 2.70-8.89, respectively). For PMDD the results were: OR = 2.61; 95%CI: 1.35-5.05 and OR = 5.79; 95%CI: 2.63-12.76, respectively. Subjects with medium and high levels of neuroticism were also at higher odds of suffering from PMS (OR = 2.53; 95%CI: 1.06-6.06 and OR = 8.05; 95%CI: 3.07-2.12, respectively). For PMDD, the results were OR = 3.70; 95%CI: 1.27-10.77 and 5.73: 95%CI: 1.96-16.77, respectively. High levels in the large majority of coping strategies were also associated with increased odds of PMS and PMDD.
Psychological factors including perceived stress, neuroticism and coping strategies are strongly related to PMS/PMDD. This association is unlikely to be due to confounding or misclassification bias. A reverse causation process cannot be ruled out although its likelihood is remote.
This paper analyses the influence of female directors on the demand for audit effort and on financial reporting quality for a sample of Australian non-financial listed firms over the period ...2004-2018. Our results suggest that gender diversity at the Board and the audit committee have a beneficial impact both on the demand of audit effort and on the outcomes of the audit process. This beneficial effect of female directors is attributable to non-executive directors. Long tenured and busy female directors and women chairing the board or the audit committee are revealed as especially influential at improving audit efforts and outcomes. We obtain further indication that audit effort and reporting quality improve from the first women added to the board not being necessary to attain a certain critical mass to generate these effects. Also, gender diversity improves the external auditor independence though the presence of lower of non-audit fees. The results are robust to endogeneity corrections. Evidence from the Australian market provides a positive argument for small and mid-cap Australian listed firms to follow the path of large Australian listed firms towards gender diversity.
Lifting operations play a key role to sustain shale gas wells productivity. Artificial Lift Systems (ALS) involve a wide range of techniques aimed at deliquifying wells. Although these operations are ...relatively mature for vertical wells in conventional reservoirs, enhancing productivity from shale gas wells has become a new frontier for unconventional production. The main contribution of this work is the development of the first Mixed Integer Linear Programming (MILP) formulation determining the integrated planning of several ALS in a multiwell pad. The model simultaneously manages ALS selection, investment and operational decisions, hedging against rapid decline curves in different wells. We introduce very detailed piecewise functions accounting for the ALS installation and removal times. The performance of the MILP is evaluated by solving five illustrative case studies.
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